feat(linter) eslint plugin unicorn: prefer string starts ends with

crates/oxc_linter/src/rules.rs

@@ -168,6 +168,7 @@ mod unicorn {
     pub mod prefer_query_selector;
     pub mod prefer_regexp_test;
     pub mod prefer_spread;
+    pub mod prefer_string_starts_ends_with;
     pub mod prefer_string_trim_start_end;
     pub mod prefer_type_error;
     pub mod require_number_to_fixed_digits_argument;
@@ -310,6 +311,7 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::prefer_regexp_test,
     unicorn::prefer_spread,
     unicorn::prefer_string_trim_start_end,
+    unicorn::prefer_string_starts_ends_with,
     unicorn::prefer_type_error,
     unicorn::require_number_to_fixed_digits_argument,
     unicorn::switch_case_braces,

crates/oxc_linter/src/rules/unicorn/prefer_string_starts_ends_with.rs

@@ -0,0 +1,173 @@
+use oxc_ast::{
+    ast::{Expression, MemberExpression, RegExpFlags, RegExpLiteral},
+    AstKind,
+};
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::Error,
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{context::LintContext, rule::Rule, AstNode};
+
+#[derive(Debug, Error, Diagnostic)]
+enum PreferStringStartsEndsWithDiagnostic {
+    #[error("eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.")]
+    #[diagnostic(severity(warning))]
+    StartsWith(#[label] Span),
+    #[error("eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#endsWith over a regex with a dollar sign.")]
+    #[diagnostic(severity(warning))]
+    EndsWith(#[label] Span),
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct PreferStringStartsEndsWith;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Prefer [`String#startsWith()`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith) and [`String#endsWith()`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/endsWith) over using a regex with `/^foo/` or `/foo$/`.
+    ///
+    /// ### Why is this bad?
+    ///
+    /// Using `String#startsWith()` and `String#endsWith()` is more readable and performant as it does not need to parse a regex.
+    ///
+    /// ### Example
+    /// ```javascript
+    /// // Bad
+    /// const foo = "hello";
+    /// /^abc/.test(foo);
+    ///
+    /// // Good
+    /// const foo = "hello";
+    /// foo.startsWith("abc");
+    /// ```
+    PreferStringStartsEndsWith,
+    correctness
+);
+
+impl Rule for PreferStringStartsEndsWith {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::CallExpression(call_expr) = node.kind() else {
+            return;
+        };
+
+        if call_expr.optional {
+            return;
+        }
+
+        let Some(member_expr) = call_expr.callee.get_member_expr() else { return };
+
+        let MemberExpression::StaticMemberExpression(static_member_expr) = &member_expr else {
+            return;
+        };
+
+        if !matches!(static_member_expr.property.name.as_str(), "test") {
+            return;
+        }
+
+        let Expression::RegExpLiteral(regex) = &member_expr.object().without_parenthesized() else {
+            return;
+        };
+
+        let Some(err_kind) = check_regex(regex) else { return };
+
+        match err_kind {
+            ErrorKind::StartsWith => {
+                ctx.diagnostic(PreferStringStartsEndsWithDiagnostic::StartsWith(call_expr.span));
+            }
+            ErrorKind::EndsWith => {
+                ctx.diagnostic(PreferStringStartsEndsWithDiagnostic::EndsWith(call_expr.span));
+            }
+        }
+    }
+}
+
+enum ErrorKind {
+    StartsWith,
+    EndsWith,
+}
+
+fn check_regex(regexp_lit: &RegExpLiteral) -> Option<ErrorKind> {
+    if regexp_lit.regex.flags.contains(RegExpFlags::I | RegExpFlags::M) {
+        return None;
+    }
+
+    if regexp_lit.regex.pattern.starts_with('^')
+        && is_simple_string(&regexp_lit.regex.pattern.as_str()[1..regexp_lit.regex.pattern.len()])
+    {
+        return Some(ErrorKind::StartsWith);
+    }
+
+    if regexp_lit.regex.pattern.ends_with('$')
+        && is_simple_string(
+            &regexp_lit.regex.pattern.as_str()[0..regexp_lit.regex.pattern.len() - 2],
+        )
+    {
+        return Some(ErrorKind::EndsWith);
+    }
+
+    None
+}
+
+fn is_simple_string(str: &str) -> bool {
+    str.chars()
+        .all(|c| !matches!(c, '^' | '$' | '+' | '[' | '{' | '(' | '\\' | '.' | '?' | '*' | '|'))
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        r#"foo.startsWith("bar")"#,
+        r#"foo.endsWith("bar")"#,
+        r#"reject(new Error("foo"))"#,
+        r#""".test()"#,
+        r#"test()"#,
+        r#"test.test()"#,
+        r#"startWith("bar")"#,
+        r#"foo()()"#,
+        r#"if (foo.match(/^foo/)) {}"#,
+        r#"if (/^foo/.exec(foo)) {}"#,
+    ];
+
+    let fail = vec![
+        r#"const foo = {}; /^abc/.test(foo);"#,
+        r#"const foo = 123; /^abc/.test(foo);"#,
+        r#"const foo = "hello"; /^abc/.test(foo);"#,
+        r#"/^b/.test((a))"#,
+        r#"(/^b/).test((a))"#,
+        r#"const fn = async () => /^b/.test(await foo)"#,
+        r#"const fn = async () => (/^b/).test(await foo)"#,
+        r#"/^a/.test("string")"#,
+        r#"/^a/.test((0, "string"))"#,
+        r#"async function a() {return /^a/.test(await foo())}"#,
+        r#"/^a/.test(foo + bar)"#,
+        r#"/^a/.test(foo || bar)"#,
+        r#"/^a/.test(new SomeString)"#,
+        r#"/^a/.test(new (SomeString))"#,
+        r#"/^a/.test(new SomeString())"#,
+        r#"/^a/.test(new new SomeClassReturnsAStringSubClass())"#,
+        r#"/^a/.test(new SomeString(/* comment */))"#,
+        r#"/^a/.test(new SomeString("string"))"#,
+        r#"/^a/.test(foo.bar)"#,
+        r#"/^a/.test(foo.bar())"#,
+        r#"/^a/.test(foo?.bar)"#,
+        r#"/^a/.test(foo?.bar())"#,
+        r#"/^a/.test(`string`)"#,
+        r#"/^a/.test(tagged`string`)"#,
+        r#"(/^a/).test((0, "string"))"#,
+        r#"/^a/.test(true ? a : b)"#,
+        r#"/a$/.test(a ??= b)"#,
+        r#"/^a/.test(a || b)"#,
+        r#"/^a/.test(a && b)"#,
+        r#"/^a/u.test("string")"#,
+        r#"/^a/v.test("string")"#,
+        r#"/a$/.test(`${unknown}`)"#,
+        r#"/a$/.test(String(unknown))"#,
+    ];
+
+    Tester::new_without_config(PreferStringStartsEndsWith::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/prefer_string_starts_ends_with.snap

@@ -0,0 +1,203 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: prefer_string_starts_ends_with
+---
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ const foo = {}; /^abc/.test(foo);
+   ·                 ────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ const foo = 123; /^abc/.test(foo);
+   ·                  ────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ const foo = "hello"; /^abc/.test(foo);
+   ·                      ────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^b/.test((a))
+   · ──────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ (/^b/).test((a))
+   · ────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ const fn = async () => /^b/.test(await foo)
+   ·                        ────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ const fn = async () => (/^b/).test(await foo)
+   ·                        ──────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test("string")
+   · ───────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test((0, "string"))
+   · ────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ async function a() {return /^a/.test(await foo())}
+   ·                            ──────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo + bar)
+   · ────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo || bar)
+   · ─────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new SomeString)
+   · ─────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new (SomeString))
+   · ───────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new SomeString())
+   · ───────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new new SomeClassReturnsAStringSubClass())
+   · ────────────────────────────────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new SomeString(/* comment */))
+   · ────────────────────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(new SomeString("string"))
+   · ───────────────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo.bar)
+   · ──────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo.bar())
+   · ────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo?.bar)
+   · ───────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(foo?.bar())
+   · ─────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(`string`)
+   · ───────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(tagged`string`)
+   · ─────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ (/^a/).test((0, "string"))
+   · ──────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(true ? a : b)
+   · ───────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#endsWith over a regex with a dollar sign.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /a$/.test(a ??= b)
+   · ──────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(a || b)
+   · ─────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/.test(a && b)
+   · ─────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/u.test("string")
+   · ────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#startsWith over a regex with a caret.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /^a/v.test("string")
+   · ────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#endsWith over a regex with a dollar sign.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /a$/.test(`${unknown}`)
+   · ───────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-string-starts-ends-with): Prefer String#endsWith over a regex with a dollar sign.
+   ╭─[prefer_string_starts_ends_with.tsx:1:1]
+ 1 │ /a$/.test(String(unknown))
+   · ──────────────────────────
+   ╰────
+
+